The invention relates to a coin testing arrangement for parking meters. When a coin is inserted into a parking meter of the type in question, a coin transporting mechanism is activated and diameter-testing and hole-testing operations are initiated and performed by means of sensing levers. These sensing levers, if the coin is sensed as having the correct diameter and as being free of holes, effect a time setting during the further course of the coin transport movement. After the sensing levers have completed the setting they transport the coins into a coin box.
Besides the generally conventional testing of the diameter of a coin to determine its genuineness, more and more use is being made of supplemental testing methods for preventing unlawful setting of the timing mechanism of automatic parking meters. To this end, there have come into use testing methods which test an inserted coin or coin-like object to determine whether it has a hole. These testing methods answer an urgent need, particularly because of the increasing use of metallic slugs deliberately employed to effect setting of the parking-time timing mechanism of the meter.
A further consideration which must be taken into account in designing a truly effective testing system is that unlawful so-called play money made of synthetic plastic has come into circulation, particularly in certain countries and localities, with such play coins having outer dimensions and surface stampings fashioned to exactly simulate those of genuine metal currency. In order to differentiate such plastic coins from similar genuine metallic coins, one possibility which has come to mind is the utilization of magnetic force fields for detecting the characteristics of iron-containing metal coins.
Known already is a considerable number of coin testing devices operative, on the basis of the action of a magnetic field in cooperation with the iron content of the coin material, for sorting coins to be tested, for routing coins into different transport channels, for rejecting unacceptable coins, etc. In most cases, these arrangements are very expensive, are composed of numerous component parts, require considerable space for installation, and accordingly are not well suited for use in parking meters.
Federal Republic of Germany Utility model DB-GM 1,745,460 discloses a simple magnetic coin testing arrangement having a magnet in the coin channel for deflecting a coin under magnetic force into a certain direction. Also, it is proposed to use a permanent magnet having the form of a circular disk so magnetized that the magnetic force lines outside extend about approximately each half of the disk. A magnetically attractable coin falls under its own weight through the field line zone of the magnetic disk and, due to the action of the attractive forces, rolls down with its rim surface upon the magnet disk. Then, a genuine coin is deflected into a coin channel after which, if the coin then passes a diameter test, activation of the parking meter is made to occur. A coin or coin-like object which is not magnetically attractable is not subjected to any deflection by the magnetic disk, but instead falls directly downwards into the coin box, without activating the parking meter.
The effectiveness of the magnetic force over the opposite circular-arc-shaped rim surfaces upon the coins is very meager, because the two surfaces in theory contact only a short line corresponding to the coin thickness. Any slug made of iron-containing metal and having coin-like dimensions passes through the arrangement without being sorted out as non-genuine. Also, it is necessary to provide two separate channels for coins, one for the genuine and the other for the not genuine coins.
Federal Republic of Germany published patent application DT-OS 2,243,221 discloses another magnetic coin testing technique. A rotatably mounted arresting lever in its rest position blocks with its one end a feeler pin for the proper-diameter determination, and with its other end, on which is carried a magnet, it extends into the coin travel path. The magnet testing lever cooperates via a pivot arm with a swingable diameter-testing device in such a manner that a diameter-sensing element (the feeler pin) is arrested in an inoperative position. The magnetic arm of the arresting lever projects, in preparation for the diameter testing, into the coin-insertion slot. Only if the inserted coin is ferromagnetic does the magnetic arresting arm, during transport of the coin and due to the attractive force between the coin and the magnetic arresting arm, become pulled along to release the feeler pin constituting the actual sensing element for the diameter-testing operation.
However, this pre-condition to the initiation of the diameter-testing operation, and thereby the setting of parking-time timing mechanism, is met by simple perforated disks so long as these have a sufficient iron content and have diameters corresponding to those of genuine coins. Additionally, the arresting lever is held in the arresting position only under the force of its own weight; as a result, slugs minted to have a special surface roughness characteristic or having surface projections can cause hooking-on, or other frictional engagement of the sides of the arresting lever, and thereby cause the arresting lever to undesirably effect the aforedescribed activation of the meter.